ASoC: pcm: Drop obsoleted PCM copy_user ops

Now all ASoC users have been replaced to use the new PCM copy ops,
let's drop the obsoleted copy_user ops and its helper function.

Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230815190136.8987-25-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>